Improving the antitumor efficiency against hepatocellular carcinoma by harmine-loaded liposomes with mitochondria targeting and legumain response

Harmine (HM) is an alkaloid contained in the seeds of Peganum harmala L. that has antimalarial and anticancer effects. Nevertheless, its low bioavailability and toxic side effects limited its clinical applications. This study used a new mitochondrial targeting peptide (KA) to modify the HM-loaded liposome (KA-HM-LPS) by pre-insert method. The KA peptide consists of a mitochondrial targeting sequence (KLA) and a legumain-cleavable sequence (AAN). The KA-HM-LPS had a small particle size of 246.2 ± 5.482 nm, a polydispersity index of 0.275 ± 0.038, a zeta potential of −15.5 ± 0.687 mV, and an encapsulation efficiency of 93.8% ± 0.96%. The drug release experiment showed that KA-HM-LPS was released more slowly than free HM in PBS buffer (pH 7.4). Cell counting kit-8 assay and intracellular uptake experiments showed that KA-HM-LPS had higher cytotoxicity and mitochondrial targeting efficiency than HM-LPS in LGMN-overexpressing SK-Hep-1 cells. The tetramethylrhodamine ethyl ester fluorescence observations suggest that KA-HM-LPS had reduced mitochondrial membrane potential. The tumor growth inhibition rate of KA-HM-LPS in vivo was as high as 67.74% ± 15.20%, which far exceeded that of free HM-LPS (33.12% ± 8.96%). Moreover, the hematoxylin and eosin staining and blood compatibility assays showed that KA-HM-LPS possessed excellent biocompatibility and hemocompatibility. Therefore, KA-HM-LPS had legumain responsiveness and mitochondrial targeting and may provide a safe and efficient therapeutic strategy for hepatocellular carcinoma.